To install add-in download the latest msi-installer (geometry_plus_plus.msi) at this link v. 0.4.0 (alpha 3).

msi-installer at GitHub release page
msi-installer at GitHub release page

Once installer restart SOLIDWORKS (if it was already started). New Geometry++ group is added to SOLIDWORKS menu, toolbar and command manager box.

Command tab box of Geometry++
Command tab box of Geometry++

Add-in checks for the update on startup. If new update is available popup message with download link is displayed.

Add-in can be uninstalled from the Add or Remove Programs group in Control Panel.